c++ 17解决方案(这将工作于std::string和std::wstring):

分配一个缓冲区，格式化它，然后复制到另一个字符串是不高效的。可以创建格式化字符串大小的std::string，并直接格式化到字符串缓冲区中:

#include <string>
#include <stdexcept>
#include <cwchar>
#include <cstdio>
#include <type_traits>

template<typename T, typename ... Args>
std::basic_string<T> string_format(T const* const format, Args ... args)
{
    int size_signed{ 0 };

    // 1) Determine size with error handling:    
    if constexpr (std::is_same_v<T, char>) { // C++17
        size_signed = std::snprintf(nullptr, 0, format, args ...);
    }
    else {
        size_signed = std::swprintf(nullptr, 0, format, args ...);
    }  
    if (size_signed <= 0) {
        throw std::runtime_error("error during formatting.");
    }
    const auto size = static_cast<size_t>(size_signed);

    // 2) Prepare formatted string:
    std::basic_string<T> formatted(size, T{});
    if constexpr (std::is_same_v<T, char>) { // C++17
        std::snprintf(formatted.data(), size + 1, format, args ...); // +1 for the '\0' (it will not be part of formatted).
    }
    else {
        std::swprintf(formatted.data(), size + 1, format, args ...); // +1 for the '\0' (it will not be part of formatted).
    }

    return formatted; // Named Return Value Optimization (NRVO), avoids an unnecessary copy. 
}

此外:通常，format参数是char[] / wchar_t[] &创建std::string对象效率不高。传递char*或wchar_t* &如果你已经有一个std::string对象，你仍然可以使用它作为your_string.c_str()。例子:

int main()
{
    int i{ 0 };

    // The format parameter is a char[] / wchar_t[]:

    const std::string title1 = string_format("story[%d].", ++i); // => "story[1]"

    const std::wstring title2 = string_format(L"story[%d].", ++i); // => L"story[2]"

    // If you already have a std::string object:

    const std::string format1{ "story[%d]." };
    const std::string title3 = string_format(format1.c_str(), ++i); // => "story[3]"

    const std::wstring format2{ L"story[%d]." };
    const std::wstring title4 = string_format(format2.c_str(), ++i); // => L"story[4]"  
}

你可以试试这个:

string str;
str.resize( _MAX_PATH );

sprintf( &str[0], "%s %s", "hello", "world" );
// optionals
// sprintf_s( &str[0], str.length(), "%s %s", "hello", "world" ); // Microsoft
// #include <stdio.h>
// snprintf( &str[0], str.length(), "%s %s", "hello", "world" ); // c++11

str.resize( strlen( str.data() ) + 1 );

从Dacav和pixelpoint的答案中获得灵感。我玩了一下，得到了这个:

#include <cstdarg>
#include <cstdio>
#include <string>

std::string format(const char* fmt, ...)
{
    va_list vl;

    va_start(vl, fmt);
    int size = vsnprintf(0, 0, fmt, vl) + sizeof('\0');
    va_end(vl);

    char buffer[size];

    va_start(vl, fmt);
    size = vsnprintf(buffer, size, fmt, vl);
    va_end(vl);

    return std::string(buffer, size);
}

通过合理的编程实践，我相信代码应该足够了，但是我仍然对更安全的替代方案持开放态度，这些替代方案仍然足够简单，不需要c++ 11。

下面是另一个版本，它使用初始缓冲区来防止在初始缓冲区已经足够多时再次调用vsnprintf()。

std::string format(const char* fmt, ...)
{

    va_list vl;
    int size;

    enum { INITIAL_BUFFER_SIZE = 512 };

    {
        char buffer[INITIAL_BUFFER_SIZE];

        va_start(vl, fmt);
        size = vsnprintf(buffer, INITIAL_BUFFER_SIZE, fmt, vl);
        va_end(vl);

        if (size < INITIAL_BUFFER_SIZE)
            return std::string(buffer, size);
    }

    size += sizeof('\0');

    char buffer[size];

    va_start(vl, fmt);
    size = vsnprintf(buffer, size, fmt, vl);
    va_end(vl);

    return std::string(buffer, size);
}

(事实证明，这个版本与Piti Ongmongkolkul的答案相似，只是它没有使用new和delete[]，并且在创建std::string时指定了大小。

The idea here of not using new and delete[] is to imply usage of the stack over the heap since it doesn't need to call allocation and deallocation functions, however if not properly used, it could be dangerous to buffer overflows in some (perhaps old, or perhaps just vulnerable) systems. If this is a concern, I highly suggest using new and delete[] instead. Note that the only concern here is about the allocations as vsnprintf() is already called with limits, so specifying a limit based on the size allocated on the second buffer would also prevent those.)

[编辑:20/05/25]更好的是… 在标题:

// `say` prints the values
// `says` returns a string instead of printing
// `sayss` appends the values to it's first argument instead of printing
// `sayerr` prints the values and returns `false` (useful for return statement fail-report)<br/>

void PRINTSTRING(const std::string &s); //cater for GUI, terminal, whatever..
template<typename...P> void say(P...p) { std::string r{}; std::stringstream ss(""); (ss<<...<<p); r=ss.str(); PRINTSTRING(r); }
template<typename...P> std::string says(P...p) { std::string r{}; std::stringstream ss(""); (ss<<...<<p); r=ss.str(); return r; }
template<typename...P> void sayss(std::string &s, P...p) { std::string r{}; std::stringstream ss(""); (ss<<...<<p); r=ss.str();  s+=r; } //APPENDS! to s!
template<typename...P> bool sayerr(P...p) { std::string r{}; std::stringstream ss("ERROR: "); (ss<<...<<p); r=ss.str(); PRINTSTRING(r); return false; }

PRINTSTRING(r)-函数是为了满足GUI或终端或任何特殊输出需要使用#ifdef _some_flag_，默认是:

void PRINTSTRING(const std::string &s) { std::cout << s << std::flush; }

[edit '17/8/31]添加可变参数模板版本'vtspf(..)':

template<typename T> const std::string type_to_string(const T &v)
{
    std::ostringstream ss;
    ss << v;
    return ss.str();
};

template<typename T> const T string_to_type(const std::string &str)
{
    std::istringstream ss(str);
    T ret;
    ss >> ret;
    return ret;
};

template<typename...P> void vtspf_priv(std::string &s) {}

template<typename H, typename...P> void vtspf_priv(std::string &s, H h, P...p)
{
    s+=type_to_string(h);
    vtspf_priv(s, p...);
}

template<typename...P> std::string temp_vtspf(P...p)
{
    std::string s("");
    vtspf_priv(s, p...);
    return s;
}

它实际上是一个逗号分隔的版本(而不是)有时阻碍<<-操作符，像这样使用:

char chSpace=' ';
double pi=3.1415;
std::string sWorld="World", str_var;
str_var = vtspf("Hello", ',', chSpace, sWorld, ", pi=", pi);

[编辑]在Erik Aronesty的回答中使用了这个技巧(上图):

#include <string>
#include <cstdarg>
#include <cstdio>

//=============================================================================
void spf(std::string &s, const std::string fmt, ...)
{
    int n, size=100;
    bool b=false;
    va_list marker;

    while (!b)
    {
        s.resize(size);
        va_start(marker, fmt);
        n = vsnprintf((char*)s.c_str(), size, fmt.c_str(), marker);
        va_end(marker);
        if ((n>0) && ((b=(n<size))==true)) s.resize(n); else size*=2;
    }
}

//=============================================================================
void spfa(std::string &s, const std::string fmt, ...)
{
    std::string ss;
    int n, size=100;
    bool b=false;
    va_list marker;

    while (!b)
    {
        ss.resize(size);
        va_start(marker, fmt);
        n = vsnprintf((char*)ss.c_str(), size, fmt.c_str(), marker);
        va_end(marker);
        if ((n>0) && ((b=(n<size))==true)) ss.resize(n); else size*=2;
    }
    s += ss;
}

(之前的回答) 这是一个很晚的回答，但对于那些像我一样喜欢“sprintf”方式的人来说:我已经编写并正在使用以下函数。如果你喜欢它，你可以扩展%-选项以更接近sprintf选项;现在里面的已经足够我用了。 使用stringf()和stringfappend()与使用sprintf相同。只要记住参数…必须是POD类型。

//=============================================================================
void DoFormatting(std::string& sF, const char* sformat, va_list marker)
{
    char *s, ch=0;
    int n, i=0, m;
    long l;
    double d;
    std::string sf = sformat;
    std::stringstream ss;

    m = sf.length();
    while (i<m)
    {
        ch = sf.at(i);
        if (ch == '%')
        {
            i++;
            if (i<m)
            {
                ch = sf.at(i);
                switch(ch)
                {
                    case 's': { s = va_arg(marker, char*);  ss << s;         } break;
                    case 'c': { n = va_arg(marker, int);    ss << (char)n;   } break;
                    case 'd': { n = va_arg(marker, int);    ss << (int)n;    } break;
                    case 'l': { l = va_arg(marker, long);   ss << (long)l;   } break;
                    case 'f': { d = va_arg(marker, double); ss << (float)d;  } break;
                    case 'e': { d = va_arg(marker, double); ss << (double)d; } break;
                    case 'X':
                    case 'x':
                        {
                            if (++i<m)
                            {
                                ss << std::hex << std::setiosflags (std::ios_base::showbase);
                                if (ch == 'X') ss << std::setiosflags (std::ios_base::uppercase);
                                char ch2 = sf.at(i);
                                if (ch2 == 'c') { n = va_arg(marker, int);  ss << std::hex << (char)n; }
                                else if (ch2 == 'd') { n = va_arg(marker, int); ss << std::hex << (int)n; }
                                else if (ch2 == 'l') { l = va_arg(marker, long);    ss << std::hex << (long)l; }
                                else ss << '%' << ch << ch2;
                                ss << std::resetiosflags (std::ios_base::showbase | std::ios_base::uppercase) << std::dec;
                            }
                        } break;
                    case '%': { ss << '%'; } break;
                    default:
                    {
                        ss << "%" << ch;
                        //i = m; //get out of loop
                    }
                }
            }
        }
        else ss << ch;
        i++;
    }
    va_end(marker);
    sF = ss.str();
}

//=============================================================================
void stringf(string& stgt,const char *sformat, ... )
{
    va_list marker;
    va_start(marker, sformat);
    DoFormatting(stgt, sformat, marker);
}

//=============================================================================
void stringfappend(string& stgt,const char *sformat, ... )
{
    string sF = "";
    va_list marker;
    va_start(marker, sformat);
    DoFormatting(sF, sformat, marker);
    stgt += sF;
}

以下是我的(简单的解决方案):

std::string Format(const char* lpszFormat, ...)
{
    // Warning : "vsnprintf" crashes with an access violation
    // exception if lpszFormat is not a "const char*" (for example, const string&)

    size_t  nSize     = 1024;
    char    *lpBuffer = (char*)malloc(nSize);

    va_list lpParams;

    while (true)
    {
        va_start(lpParams, lpszFormat);

        int nResult = vsnprintf(
            lpBuffer,
            nSize,
            lpszFormat,
            lpParams
        );

        va_end(lpParams);

        if ((nResult >= 0) && (nResult < (int)nSize) )
        {
            // Success

            lpBuffer[nResult] = '\0';
            std::string sResult(lpBuffer);

            free (lpBuffer);

            return sResult;
        }
        else
        {
            // Increase buffer

            nSize =
                  (nResult < 0)
                ? nSize *= 2
                : (nResult + 1)
            ;

            lpBuffer = (char *)realloc(lpBuffer, nSize);
        }
    }
}

_return.desc = (boost::format("fail to detect. cv_result = %d") % st_result).str();